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Ginko may 'help boost brain recovery after stroke' researchers report

"Herbal supplement found on the High Street for £4.99 can boost memory, strength and speech in stroke survivors, study reveals," reports the Mail Online. This follows a new trial from China investigating whether Ginkgo biloba extract (GBE) could help recovery after stroke. 

Ginkgo biloba is an ancient Chinese tree species whose extract is used in Chinese medicine. It is widely available in the UK.

Supporters of Chinese herbal medicine claim that gingko is effective for many conditions, ranging from memory loss to tinnitus. But conclusive evidence is thin on the ground. 

The trial included 348 people who'd had a stroke where a blood clot interrupts the blood supply to the brain. Strokes can cause physical problems and can also affect cognitive skills such as memory and concentration.

The study found that people who took GBE alongside aspirin for 6 months had around a 1-point greater improvement on a 30-point cognitive assessment compared to those who took just aspirin. Whether this difference is significant is another matter.

It should be noted that the researchers were not blinded – they knew who was taking ginkgo – which could introduce an element of bias. 

Also, long-term outcomes and possible adverse effects weren't examined. Ginkgo biloba can interact with several other drugs and is known to have blood-thinning properties. People recovering from stroke shouldn't take GBE without consulting a health professional.

Where did the story come from?

The study was led by a team of researchers from Nanjing University Medical School in China and was funded by the National Natural Science Foundation of China, the Science and Technology Department of Jiangsu Province and Jiangsu Province Key Medical Discipline.

The study was published in the peer-reviewed medical journal Stroke and Vascular Neurology. It's available on an open access basis and is free to read online.

The Mail Online's coverage on this study was far too optimistic. It went as far as quoting the price of the herbal remedy in the UK and did not highlight any of the study's limitations. 

BBC News had a more balanced and accurate report that included a quote from Dr David Reynolds, Chief Scientific Officer of Alzheimer's Research UK, who was critical of the methodology used in the study. 

What kind of research was this?

This was a randomised controlled trial (RCT) to investigate whether Ginkgo biloba extract (GBE) could be a safe and effective treatment for people recovering from ischaemic stroke (a stroke caused by a blood clot or another cause of lack of blood supply to the brain).

RCTs are one of the best ways to test the effectiveness of a therapy for any condition. 

What did the research involve?

The researchers recruited 348 patients from 5 hospitals in China from October 2012 to June 2014. 

Participants had to be adults who had experienced an acute ischaemic stroke in the previous 7 days (average age 65 years, 68% women). Anyone with history of brain bleeds, severe heart, kidney or liver problems, or severe cognitive impairment was excluded.

Participants were randomised to 6 months treatment with: 

  • 3 daily doses of 150mg Ginkgo ketone ester dispersible tablets alongside a daily dose of 100mg aspirin
  • 100mg of aspirin alone

The main outcome measured was cognitive decline on the 30-point Montreal Cognitive Assessment (MoCA) at 180 days. MoCA consists of a series of tests designed to test memory and cognitive function, such as repeating back a short list of words or reproducing a geometric sketch. 

The assessment was also performed at the start of the study and after 12, 30 and 90 days. Lower scores indicate a more serious degree of cognitive function impairment. 

The researchers also assessed patients with: 

  • the National Institutes of Health Stroke Scale (NIHSS) and modified Rankin Scale (mRS) independent rate which are used to assess clinical severity and functional ability
  • the Barthel Index (BI) which measures global function and daily activities
  • Mini-Mental State Examination (MMSE) to test cognitive function
  • neuropsychological testing for executive function using the Executive Dysfunction Index (EDI) and Webster's digit symbol test (WDT)

They also looked at: 

  • adverse events within 6 months of treatment
  • further vascular events such as ischaemic stroke or transient ischaemic attack (TIA), and cardiovascular events such as heart attack, 1 to 2 years post stroke

What were the basic results?

All the participants' MoCA scores had declined by 180 days post stroke, but the GBE group had a 1.29 higher score meaning they were doing slightly better (a 2.71 point decline vs 4 point decline among controls). The difference between groups was similar at earlier time-points. 

There were also slightly more improvements in the GBE group compared to the control in the other tests measured at 30, 90 and 180 days. 

There was no significant difference in the rate of adverse events or further vascular events between the two groups.

How did the researchers interpret the results?

The researchers concluded: "GBE in combination with aspirin treatment alleviated cognitive and neurological deficits after acute ischaemic stroke without increasing the incidence of vascular events."

Conclusion

This Chinese trial found that GBE used alongside aspirin resulted in slightly greater improvements in cognitive tests for people with ischaemic stroke, than treatment with aspirin alone. 

The researchers suggest ginkgo biloba may be a promising treatment for people with ischaemic stroke. 

However, there are important limitations to bear in mind:

  • The difference between scores was tiny – just a 1-point improvement on a 30-point scale. It's questionable how much difference this would make to the person's daily life and functioning and whether this is worth the potential risks. 
  • The researchers were aware of the treatment given so the analysis and conclusions run the risk of being biased.
  • The trial had a relatively small sample size with a short follow-up. Further research with a larger number of participants followed up for longer is needed to really understand the effects of using GBE, including any adverse effects.
  • Ginkgo biloba interacts with many other medications and has various potential effects, including altering blood pressure, blood sugar balance and making the blood less likely to clot. GBE should definitely not be taken by people who have a history of bleeds (including haemorrhagic stroke), and would not normally be advised for people taking aspirin or other blood-thinning medicines. 
  • Complementary or herbal medicines can often be seen as "safe" and without side effects, but this isn't necessarily the case. In fact, often they aren't subject to the same rigorous testing as medical drugs to ensure they're safe and effective. 

For now, using Ginkgo biloba extract, or other herbal remedies, is not recommended as a treatment for people recovering from a stroke.

Analysis by Bazian 
Edited by NHS Choices

Links to the headlines

Herbal remedy for stroke recovery?

BBC News, December 19 2017

Herbal supplement found on the High Street for £4.99 can boost memory, strength and speech in stroke survivors, study reveals

Mail Online, December 19 2017

Links to the science

Li S, Zhang X, Fang Q, et al. Ginkgo biloba extract improved cognitive and neurological functions of acute ischaemic stroke: a randomised controlled trialStroke and Vascular Neurology. Published online December 18 2017